This invention relates generally to a grommet strip for covering an exposed edge of a wall and, more particularly, to an electrically insulating grommet strip for covering the exposed edges of openings in electrical equipment housings.
Electrical equipment housings frequently possess openings for the passage of electrical wires. Generally, such openings are equipped with grommets or bushings that cover and insulate the exposed edges of the openings. A common grommet is made of rubber or a similar resilient material and consists of a pair of annular spaced apart flange portions internally joined by a cylindrical portion. The cylindrical portion projects through an opening and the flange portions engage the peripheral wall portions thereof. Disadvantages of such grommets include the requirement for large inventories to accommodate openings of various size, and their inapplicability to openings of other than circular shape.
The above problems are somewhat alleviated by a grommet strip having a flat, elongated base from opposite edge of which project longitudinally spaced apart fingers. The strip can be cut to desired length and then applied to an opening with the base engaging the edge of the opening and the fingers engaging peripheral portions thereof. Such a grommet strip is disclosed in British Patent No. 849,761. However, certain disadvantages persist for even the above described grommet strip. For example, the installation of the grommet strip into openings of complex shape requires the use of an adhesive and is, therefore, quite labor intensive.
An improved grommet strip that does not require the use of adhesives for installation is disclosed in U.S. Pat. No. 4,769,966. Although satisfactory for many applications, the grommet strips disclosed in that patent do have disadvantages in certain applications. For example, a U-shaped resilient channel covering the base of a metal strip exhibits an undesirable tendency to bulge transversely when applied to severely curved wall sections. Also, raw metal portions of the metal strip not covered by the resilient channel can damage the fingers of installers. Another grommet strip disclosed in the patent provides an electrostatic coating over the entire surface of a metal strip. In certain circumstances small diameter wires such as the fiber optic wires used in the communications industry can catch under castles in the stamped metal strip, particularly when the wires run parallel to a plane of the sheet metal to which the grommet is applied.
The object of this invention, therefore, is to provide an improved grommet for covering the exposed edges of openings in electrical housings.